Quarter-tone keyboard musical instrument



March 29, 1932. F. A. e. FbRsTER 1,851,168

QUARTER TONE KEYBOARD MUSICAL INSTRUMENT Filed March 6 1950 4 Sheets-Sheet l /5 y KTOR EY March 29, 1932. F A G C R 1,851,168

QUARTER TONE KEYBOARD MUSICAL INSTRUMENT Filed March 6, 1930 4 Sheets-Shae? 2 March 29, 1932. F G ORS R 1,851,168

QUARTER TONE KEYBOARD MUSICAL INSTRUMENT Filed March 6, 1930 4 Sheets-Sheet 3 Fig. 6.

ym w 6% March 29, 1932. FQRSTER 1,851,168

QUARTER TONE KEYBOARD MUSICAL INSTRUMENT Filed March a, 1930 4 Sheets-Sheet 4 Fig. 5.

' gig Patented Mar. 29, 1932 UNITED STATES NT OFFICE QUARTER-TONE KEYBOARD MUSICAL INSTRUMENT Application filed March 6, 1930, Serial No. 433,547, and in Germany December 4:, 1929.

In order to provide a convenient arrangementof wires or strings necessary for the production of 175 tones, it has previously been essential to employ two. methods, that 5 is, the placing beside one another or behind one another (with grand pianos above one another) of two sounding bodies, of which the one was tuned throughout a quarter of a tone highter than the other. The disadvantages of these arrangements lie in the long connections from the key to the mechanism, also in the tone-production of successive half and quarter tones at distantly removed points, and finally in a complicated and heavy meth- 0d of construction. An arrangement, which externally and internally represents the nearest possible approximation to a normal instrument, is therefore desirable.

The conditions for this are: combination of all strings on a normally proportioned sounding board, and the shortest possible connections to the keys and mechanism without auxiliary levers, tension connections, or similar connecting members which require power.

In order to attain this object, the use of cross-strung sounding bodies is not practicable, as the hammer-heads arranged obliquely, do not enable any reduction in the width to be eifected. Further, it is necessary to avoid any break in the consecutive order of the large number of notes.

According to the present invention, there is chosen as the basis for the construction of a quarter-tone keyboard instrument a form oi string arrangement in which the compacting of the wide mass is rendered possible to the greatest extent. This is the case with a straight-strung or only slightly inclinedstrung arrangement of the stringing.

It might appear that this me hod is a backward step in the development of the quartertone keyboard instrument. But against it is to be set the fact that the difference in tone between an old straight-strung instrument and a modern overstrung sounding body is in no way based only on the arrangement of the string direction, but this difference is brought about mainly by improvements in the whole of the construction of the sounding board, as well as by better material and diflerent dimensioning of the stringing and of the hammer heads. As the overstrung system was invented mainly for smaller instruments in order to obtain a greater length of the bass strings, it is not specified in the present case whether to make the whole instrument higher or longer.

According to the invention, the arrangement of a single sounding body is perfected-- by the side of the iron plate facing the mechanism being kept free from stitfenings.

The static construction of the sounding body must accordingly be carried out in a different manner from the previous method of construction, for which various materials are available. The metal frames are c0nveniently made of two parts which are connected with one another by a number of stiffening bridges led backwards through the soundingboard.

After the preliminary conditions for a considerable reduction of the total breadth of the sounding body have been secured in this way, the question arises as to the most favorable conditions for a normal manner of carrying out the construction of the mechanism and key-board. As the front division of the key-board with an octave span of about 17 cm. is in its entirety about 125 cm. wide, it isnecessary to make the bending-out of the keys, so which is nearly always present upon both sides, as small as possible so that the insertion of special coupling members is unnecessary. This requirement is however incompatible with the requirement of a normally constructed mechanism, as the mechanical members should not be chosen too narrow, in order to avoid side play on the axes. The conscientious balancing of these mutually opposed requirements, so that, as a result all the parts may be made of a normal type but with different measurements, forms therefore the most essential characteristic of the invention.

A way in which the invention may be carried out, by way of example, takes as initial measurement a string spacing of 10 mm. from which is derived a total breadth of the string division of cm. for a 17 5 string instrument. There is then a maximum bendingout of the two end keys of 25 cm. which with wane...

a sutficient length of the keys gives a bending angle which is practically quite well capable of being carried out. The mechanical members would have a cover breadth of 9.5 mm. while the hammer heads with 8.5 mm. have quite sufficient breadth.

If all the keys lie in one plane and are therefore correspondingly narrow, then the lateral guiding. of the key levers according to the manner commonly used is naturally not possible. It is'therefore proposed to secure the guide pins in the keys themselves, and to arrange the padded guide slots in frames lying underneath as the slots have more room in the framework since they are made to alternate with one another.

In the drawings there is illustrated a quarter-tone keyboard instrument according to the invention in which Fig. 1 is an example of the method of constructing the stringlay-out for a quarter tone piano.

Fig. 2 is a plan of the sounding body.

' Fig. 3 a section on the line III-III of Fig. 2, while Fig. 4 shows diagrammatically the keyboard arrangement in plan view.

Fig. 5is a side view, and

Fig. 6 a plan of the key-lever arrangement.

The sounding body has in front the two iron plates a and 6. Iron slats 0 c are arranged before and behind the stop posts, of

known type, 0?. Into both slats are screwed bolts 0, which terminate in the iron frame parts a and b and unite these with one another in a similar manner to the usual props previously led over the bridge f. The greatest lateral bending-out of the keys is marked with-g, (Fig. 4). If, for example, the total 7 posts and rigidly connecting said plates with said string plate at opposite sides of said 3. In a stringed musical instrument, a plurality of stop posts, a string plate disposed in front of said stop posts and provided with a gap therein, a pair of metal plates extending across the instrument and engaging the stop posts respectively at the front and rear sides of said posts, and a plurality of pins rigidly connecting said metal plates with said string plate at opposite sides of said gap.

4. In a stringed musical instrument, a plurality of stop posts, a string plate disposed in front of said stop posts and provided with a gap therein, a pair of metal plates eXtend ing over the entire width of the instrument, one at the front and the other at the rear of the stop posts, and two rows of pins pass-.

forcing means disposed at the rear of saidstring plate, and means rigidly connecting said posts and reinforcing means with said string plate at opposite sides of said gap.

In testimony whereof I affix my signature.

FRANZ AUGUST GERHARD FDRSTER.

breadth h of the strung section be 175 cm., I

and the total breadth z of the keyboard about 125 cm., then the maximum distance 9 to which thetwo end keys are bent out is about 25 cm. each.

The narrow keylevers is, lying in one plane, are provided with pins Z, which cause a lateral guiding of the keys in padded slots m of the frame n.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In a stringed musical instrument, a plurality of stop posts, a string plate disposed in front of said stop posts and provided with a gap therein, bridge-like reinforcing means engaging said posts at the rear of said string plate, and means rigidly connecting said reinforcing means with said string plate at opposite sides of said gap.

2. In a stringed musical instrument, a plurality of stop posts, a string plate disposed in front of said stop posts and provided with V, a gap therein, a pair of metal plates disposed a pairof pins passing through each of said V on said posts at opposite sides thereof, and 

